1. Field of the Invention
The present invention relates to a polyamide resin composition and molded products made therefrom. The polyamide resin composition of the present invention has good flame retardancy, good chemical resistance, good surface appearance and good blistering resistance, and is therefore suitable for applications that require flame retardancy and good mechanical properties, for example, for industrial materials, engineering materials, household utensils, components of electric and electronic appliances, automobile parts, etc.
2. Description of the Related Art
Aliphatic polyamides such as nylon 6 and nylon 66 are widely used for engineering plastics because they have good heat resistance, good chemical resistance, high stiffness, good abrasion resistance and good moldability. In the field of electrical devices and electronics, engineering plastics are required to have high flame retardancy, and various methods of making them resistant to flames by adding various flame retardants have been proposed and put into commercial use. However, since aliphatic polyamides absorb water, articles molded from them vary in dimension and have changing physical properties (usually for the worse). The recent trend in the field of electrical devices and electronics is to require flame retardancy, due to the development of surface mounting techniques (SMT). However, conventional polyamide resins are unsuitable for SMT applications because their heat resistance is unsatisfactory.
Consequently, semiaromatic polyamides, which are polyamides consisting essentially of an aliphatic alkylenediamine reacted with terephthalic acid, have higher heat resistance, and are therefore used for electrical and electronic applications requiring flame retardancy. For example, JP-A 239755/1991, 96970/1992, 320503/1993 and 263985/1994, propose polyamide resin compositions comprising a semiaromatic polyamide and a polybromostyrene flame retardant. However, the semiaromatic polyamide has poor compatibility with the polybromostyrene, and therefore the polybromostyrene flame retardant is not well dispersed in the resin compositions. As a result, molded products prepared from such polyamide resin compositions often have the problem of low chemical resistance and a surface which is often peeled and roughened. These problems are serious in colored molded products, because the roughened surface is whitish and has a poor appearance.
Accordingly, it is an object of the present invention to provide a polyamide resin composition, and molded articles prepared therefrom, having good flame retardancy, good chemical resistance, good surface appearance and good blistering resistance. Polyamide resin compositions having good flame retardancy, good chemical resistance, good surface appearance and good blistering resistance can be prepared by adding a polybromostyrene having an epoxy group, to a semiaromatic polyamide. Specifically, the present invention is polyamide resin composition comprising 100 parts by weight of a polyamide resin (A), that comprises repeat units derived from a dicarboxylic acid (a), which comprises from 60 to 100 mol % of repeat units derived from terephthalic acid, and repeat units derived from a diamine (b), which comprises from 60 to 100 mol % of repeat units derived from a C6-18 aliphatic alkylenediamine, and from 1 to 100 parts by weight of a polybromostyrene (B), in which from 0.5 to 100% by weight of the polybromostyrene (B) is a polybromostyrene having an epoxy group.
It is another object of the present invention to provide molded articles of the polyamide resin composition of the present invention.